Ringer and In-Call Volume problemGeneral

I recently picked up a used Eris and love it. It's my first Android phone, and it works flawlessly--most of the time. My main issue is the volume settings. None of them actually adjust; my ringer and notifications ring at full volume all the time and my In-call volume is absurdly loud. I have searched this forum and have found many have issues with low volume. My problem is the opposite. I have tried adjusting the volume in the settings screen and while on the phone talking to somebody. Neither works. While adjusting the ringer volume, it just rings at the loudest volume all the time. My firmware version is 2.1. Please help!